When illuminance is weak, a photovoltaic (PV) module only supplies DC electricity with a lower power value to an inverter. Herein, the inverter may have lower conversion efficiency because of the power consumption of the control circuit in the inverter. In addition, since the input of the inverter is a DC type but the output of the inverter is an AC type, when the PV module provides stable DC electricity to the inverter, the input of the inverter will be affected by ripples caused by the output of the inverter. Therefore, under weak illumination condition, the power generation system cannot achieve its maximum output power.
Accordingly, it is necessary for the inverter to maintain its output power and have a better conversion efficiency to increase the accuracy of tracking the maximum output power when the PV module provides low power.